1. Field of the Invention
The present invention relates generally to a wireless power transmission technology applied to wireless charging, and more particularly, to a resonance terminal device for reducing electromagnetic interferences with an antenna for Near Field Communication (NFC) in a reception system of a resonant Wireless Power Transmission (WPT) technology.
2. Description of the Related Art
In recent years, wireless charging (or noncontact charging) technologies using wireless power transmission have been developed and utilized in many electronic devices. One of the wireless charging technologies is a system by which a battery is automatically charged, for example, only by positioning the battery on a charging deck without connecting the mobile phone to a charging connector.
The WPT technologies largely include an electromagnetic induction method using coils, a resonance method using resonances, and a Radio Frequency (RF)/microwave radiation method for converting electrical energy into microwaves to transfer the electrical energy. In the power transmission method using electromagnetic induction, electric power is transmitted between a primary coil of a transmission unit and a secondary coil of a reception unit. The resonance method utilizes frequency resonances between a transmission unit and a reception unit using a resonance frequency. The wireless power transmission technology using resonance is applied to the present invention.
Studies on the WPT technology for wireless charging of portable terminals are currently underway. That is, a portable terminal includes a detachable or embedded battery pack, and commercialization of techniques for a convenient wireless charging function using the wireless power transmission technology are being developed.
Traffic cards, security cards for verifying incoming and outgoing people, and credit cards make transactions or are user-verified by using NFCs, and the NFC function is also mounted to portable terminals. Thus, a portable terminal includes a separate antenna for performing the NFC function. The NFC technology is disclosed in Korean Unexamined Patent Publication No. 2009-126323 (published on Dec. 8, 2009).
In order to mount the NFC function and a wireless charging function to one terminal, an NFC antenna having a generally loop-shaped antenna structure and a resonator for wireless charging should be mounted to the terminal. However, problems arise from interferences between the NFC antenna and the WPT resonator.